def show_message(messages):
    for message in messages:
        print(message.title())

def send_messages(messages,sent_messages):
    while messages:
        sent_message=messages.pop()
        print(f"Sending message :{sent_message}")
        sent_messages.append(sent_message)

messages=['Hello','thank you','how are you']
sent_messages=[]
show_message(messages)
send_messages(messages[:],sent_messages)
show_message(messages)#此处为空，故不在终端显示出打印结果
show_message(sent_messages)
